Two directors of Australia's main share market operator have quit after becoming embroiled in a financial scandal in the United States.

Russell Aboud and Shane Finemore will leave the Australian Securities Exchange after their investment firm, Manikay Partners, was fined by US Securities and Exchange Commission.

Manikay was one of 23 firms fined for breeching a ban on short-selling shares during 2009.

The ASX chairman Rick Holliday-Smith has released a statement saying the pair's decision does not raise concerns about the governance of the ASX.

"While the matter that triggered their decision does not raise concerns in relation to the governance of ASX, they made their decision after careful consideration of the best interests of the company," he said.

"We wish them well. ASX has an ongoing program of board renewal and this process will now be used to find suitable replacements in the coming months."

SEC says Manikay earned $US1.6 million through trades

In a statement on the ruling, the SEC says Manikay made a profit of $US1.6 million by short-selling 2 million Citigroup shares in December 2009.

The firm has been ordered to pay a total of $2.5 million dollars of fines at the start of next month.

The director of the Centre for Corporate Law at Melbourne University, Professor Ian Ramsay, says it is an important case.

"That enforcement action then has consequences internationally when two directors of ASX believe its in the best interests of ASX for them to resign their positions because of their association with the US company," he said.